Factors influencing householder self-evacuation in two Australian bushfires. A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Kenneth William Strahan B. Com (Hons) (UWA), M. Com (UWA) School of Mathematical and Geospatial Sciences College of Science Engineering and Health RMIT University April 2017 i Declaration I certify that except where due acknowledgement has been made, the work is that of the author alone; the work has not been submitted previously, in whole or in part, to qualify for any other academic award; the content of the thesis is the result of work which has been carried out since the official commencement date of the approved research program; any editorial work, paid or unpaid, carried out by a third party is acknowledged; and, ethics procedures and guidelines have been followed. I acknowledge the support I have received for my research through the provision of an Australian Government Research Training Program Scholarship. Kenneth William Strahan 24 April 2017 ii Acknowledgements Many residents of the Perth and Adelaide Hills provided their time and insights of bushfire experience, for which I am forever grateful. The guidance and encouragement provided by Professor John Handmer and Dr. Josh Whittaker to a somewhat out-of-academic-practice but enthusiastic old guy is warmly appreciated. Thank you also to the academic and administrative support from the School of Geospatial and Mathematical Sciences and to Dr Stuart Watson for his assistance with quantitative analysis. I accept full responsibility for the views expressed in this thesis and any errors or inaccuracies it contains. I wish to sincerely thank Alan Rhodes of EMV and John Gilbert of the CFA for the opportunity they provided for me to translate a work interest into a life passion. In recent years Rohan Carboon has been a colleague and a mate who has constantly reminded me of the importance of the bushfire work that we do. Finally, I wish to thank my family for their support for my academic interests over many eventful and demanding years. Thanks to Mum and Dad, my sister Judith and brother-in-law Graeme, Declan and Antaya my children, and to Urszula whose interest kept me going. iii Table of Contents Chapter 1: Introduction .............................................................................................................. 4 1.1. BUSHFIRE SELF-EVACUATION ...................................................................................... 4 1.2. RESEARCH CONTEXT AND OBJECTIVES ........................................................................ 8 1.3. RESEARCH METHODS ................................................................................................... 9 1.4. RESEARCH OUTCOMES ............................................................................................... 10 1.5. STRUCTURE OF THE THESIS ........................................................................................ 11 Chapter 2: Deciding to Evacuate from a Natural Hazard ........................................................ 13 2.1. INTRODUCTION ........................................................................................................... 13 2.2. FUNDAMENTALS OF DECISION THEORY ..................................................................... 13 2.3. DECISION THEORY AND HAZARD DECISION-MAKING ................................................ 18 2.3.1. Identifying/generating alternative actions. ....................................................... 19 2.3.2. Constructing subjective probability judgments. ............................................... 19 2.3.3. Constructing utility judgments. ......................................................................... 20 2.3.4. Search for additional information. ................................................................... 21 2.4. EXPECTANCY-VALENCE THEORETICAL MODELS ....................................................... 22 2.5. PROTECTIVE ACTION DECISION MODEL (PADM) ...................................................... 24 2.5.1. Environmental cues. .......................................................................................... 26 2.5.2. Social cues. ....................................................................................................... 27 2.5.3. Warnings. .......................................................................................................... 28 2.5.4. Pre-decisional processes. ................................................................................. 29 2.5.5. Perceptions of threats, protective action, and stakeholders. ............................ 29 2.5.5.1. Perceptions of threat. ...................................................................................... 29 2.5.5.2. Intrusiveness of threat. ................................................................................... 30 2.5.5.3. Hazard experience. ......................................................................................... 31 2.5.5.4. Hazard proximity............................................................................................ 32 2.5.6. Perceptions of hazard adjustments. .................................................................. 32 2.5.7. Perceptions of social stakeholders.................................................................... 33 2.5.8. Protective action decision-making. ................................................................... 34 2.5.8.1. Risk awareness. .............................................................................................. 34 2.5.8.2. Risk assessment. ............................................................................................. 34 2.5.8.3. Protective action search. ................................................................................. 35 2.5.8.4. Protective action assessment. ......................................................................... 35 2.5.8.5. Protective action implementation. .................................................................. 35 2.5.9. Situational impediments and facilitators. ......................................................... 36 2.5.10. Information needs and communication action assessment and implementation. 36 2.6. EVACUATION FROM A BUSHFIRE ................................................................................ 37 2.6.1. Evacuate or stay and defend. ............................................................................ 38 2.6.2. Wait and see. ..................................................................................................... 40 2.6.3. Evacuating late. ................................................................................................ 41 iv 2.6.4. Factors influencing self-evacuation. ................................................................. 41 2.6.5. Hazard adjustments (mitigation) and evacuation. ............................................ 42 2.6.6. Mathematical modelling of evacuation. ............................................................ 42 2.6.7. Characteristics of evacuators and remainers. .................................................. 43 2.6.8. Predicting self-evacuation. ............................................................................... 44 2.7. CONCLUSIONS ............................................................................................................ 44 Chapter 3 Methodology ........................................................................................................... 47 3.1. INTRODUCTION ........................................................................................................... 47 3.2. PHILOSOPHICAL FRAMEWORK .................................................................................... 47 3.2.1. Ontology. ........................................................................................................... 48 3.2.2. Epistemology. .................................................................................................... 48 3.3. MIXED-METHODS RESEARCH STRATEGY ................................................................... 52 3.4. POPULATION AND SAMPLE ......................................................................................... 54 3.5. DEVELOPMENT OF INSTRUMENTS ............................................................................... 56 3.5.1. Measures. .......................................................................................................... 57 3.6. DATA COLLECTION .................................................................................................... 58 3.6.1. Data collection in the Perth Hills. .................................................................... 58 3.6.2. Data collection in the Adelaide Hills. ............................................................... 58 3.7. DATA ANALYSIS ........................................................................................................ 66 3.7.1. Quantitative analysis. ....................................................................................... 66 3.7.2. Qualitative analysis. ......................................................................................... 67 3.8. ETHICS ....................................................................................................................... 69 3.9. DELIMITATIONS AND LIMITATIONS ............................................................................ 71 3.10. CONCLUSIONS..........................................................................................................